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End Note to Chapter 10

The Gnarled Saga of the NCP Canal

EN 10.1: The Canal 

The total water available for diversion from the Mahaveli basin in an average year is about 2,350 billion acre feet (2900 mcm) along with 700 mcm from medium-sized reservoirs in the system. Phase III, the NCP Canal, was to complete the Mahaveli project by bringing additional water to the North if feasible. The original NCP Canal in the 1969 Master Plan had been dropped along with the peasant settlements envisaged owing to water scarcity. But this has not deterred the Rajapakse government from proceeding with Sinhalese settlements in the North. In settlements that lock the settlers into poverty with no prospect of social advancement, water demands become increasingly insatiable. Even if the entire 1470 mcm p.a. of water generating hydropower at Victoria Reservoir is diverted to save the settlements, any relief would be merely transient.   

Originally, the Canal was to proceed north along the island’s central ridge, first to discharge on its left bank into Kapirigama Reservoir in Horawapotana, which connects with Malwathu Oya (Aruvi Aru). Then a little further north on the right bank into Yan River, and further on, east of Vavuniya, on the right bank into the proposed Mukunu and Kitulgala Tanks, which connect with Padaviya and System L. Finally, on reaching its northern extremity, it was to discharge into Kanagarayan River, which connects with Iranamadu Tank ( ).

The NCP canal was meant to provide water for Mahaveli Systems I (Aruvi or Malwathu River basin, Anuradhapura and Mannar Districts), J (Northwest Vanni), K (North Central Vanni, Kanagarayan Aru basin), L (Northeast Vanni – Padaviya North and Manal Aru), and M (North Trincomalee and NCP – Yan River basin). The Canal was in the Master Plan meant to develop 324,000 acres or 131,000 ha (Ratna S. Cooke, Accelerated Mahaveli Development Project, Institution of Engineers Sri Lanka, 1982). But the project developed in such a way that owing to strong preference by farmers, crops other than rice have been largely ruled out, making the annual water requirement of 2,440 mcm from the NCP Canal in the Initial Assessment Report[1] (IAR) by far out of the question.[2]   

The current policy of extending settlements northward with far too little water, means that the original Sinhalese beneficiaries in System H of the NCP who face inbuilt shortages, have no recourse to rectify their scarcity. The original Master Plan gave low priority to Phase III and had doubts about its feasibility. “After meeting the irrigation demand in Phases I & II [which includes System H], the surplus water is recommended for diversion to the North Central parts of the island in Phase III” (Ratna Cooke, ibid).

To those who identified with the political agenda of the Mahaveli Project in the early 1980s and writhed under the humiliations it brought them, the end of the war in 2009 seemed too good an opportunity to miss. The agenda is based on Systems I, J, K and L of the Mahaveli Master Plan. By 2011, the Sri Lankan Army was quietly directed to ready the ground through land acquisitions. Some of the key milestones during 2012 are:



Significant Administrative Changes & Land Aggression

 A means used to advance Sinhalisation was for the Military to take control of local water sources and land in strategic locations. A precursor to the fate of Tamils in Weli-Oya was the Air Force dominating the Mudalikulam-Morawewa head works in Trincomalee District from the latter 1960s.[3] The Vanni recently saw two significant administrative changes. On 21st November 2011 Sarath Ravindra was appointed GA Mannar, followed on 21st May 2012 by Mr. Bandula Harischandra as GA Vavuniya. The Malwathu (Aruvi) scheme (System I) comes under them. Back in the 1960s, the appointment of Sinhalese GAs to the majority Tamil-speaking districts of Trincomalee and Amparai facilitated the induction of Sinhalese settlers into new colonisation schemes. Sarath Ravindra was later moved out because he did not conform to the agenda he was meant to enforce and replaced with an ex-military officer (Ch.9).


EN 10.2: Systems I, J & K and the Sri Lankan Army’s Land Acquisitions


System I: The area west of Vavuniya was already targeted by JOSSOP (Joint Special Services Operations) as soon as it began operations in October 1983. It evicted Hill Country Tamil refugees settled on lands held on permit by Tamils (Appendix 9).


At the end of September 2012, Manik Farm was cleared of IDPs from the recent war. The Sunday Times (30 Sept. 2012) reported that top Sinhalese officials including the new GA Vavuniya, Harishchandra, met to decide on the disposal of 6,000 acres of lands directly below the Malwathu dam site at Kappachchi (see Appendix 9).[4] 


System J: The Uthayan daily of 21st January 2012 gave details of lands taken over by, or on request from, the Sri Lankan Army.[5] These areas come within settlement schemes under Pali Aru and Parangi Aru (System J).


Among the uses of the military to spearhead changes is to turn independent or potentially independent farmers into wage labourers for private capital. In Thevamutty, Vellankulam, the permit holders had left or become refugees and the LTTE had cultivated a large measure of the land. After the war, the Agriculture Department was the first to clear the land intending to use local people to restore it, and in time making them owner-cultivators. On learning of this, a government order from high up forced the Agriculture Department to desist. Using the land powers the Governor exercises in lieu of the vacant provincial council, the President’s son Namal Rajapakse gave 100 acres of the land to the private company CIC, to open its Seed and Planting Material Production Farm. The people now work for the CIC as wage labourers as they had previously done for the LTTE. This area is downstream of the projected Pali Aru reservoir.


System K: Four thousand acres of land have been taken over in Murukandi and Kilinochchi to build a new military cantonment, dispossessing inhabitants of three villages (Ranga Jayasuriya in Lakbimanews, 25 July 2010). The Army Commander said at Suthanthirapuram (22 July 2010), “… once married quarters of the officers and the other ranks are set up in respective areas, they would… live with their families… while serving the areas (” Media reports spoke of 12,000 prefabricated army houses in the three confiscated villages in Murikandi. “The implication is that the soldiers, instead of serving short stints in the North (as is the norm), will become permanent settlers together with their families, ushering in a new wave of state-aided and mandated colonisation (Tisaranee Gunasekara, Sunday Leader 1 August 2010).” 


The lands mentioned above, confiscated from Tamils, lie downstream (north) of Kanagarayan Aru (River), where the System K dam has been planned. Similarly 900 acres have been ear-marked with housing for 450 soldier families at Akkarayan.


 EN 10.3: Example of System I: Phony Schemes and Parching of the North

From about 2007 until May 2012, the Rajapakse government was loquacious on reviving the NCP Canal Project of the Mahaveli Scheme. The proposed Malwathu dam on Aruvi River, System I of the NCP Canal Project, and further irrigation works in Mannar District were advertised with much fanfare and the President was billed to declare open the construction of the dam. The Mannar farmers were promised water for 40,000 acres under Giant’s Tank and Akatthimurippu Kulam[6] to cultivate round the year, requiring 490 mcm of water. And then it all vanished into silence. The Japanese who agreed to fund the Moragahakande dam, had pulled out in early 2011. Minister de Silva’s Island interview of 1st October 2012 (‘Moragahakanda: Govt. opted for China as Japan delayed funding’) confirmed the abandonment of the Canal once more. But he still insisted on the construction of Malwathu Reservoir to take over from the NCP Canal the task of supplying water for System K on Kanagarayan River north of Vavuniya. Neither the Minister, nor anyone else in authority, has disclosed where the additional water needed would come from.

What was clear is that the Government had made plans for large Sinhalese settlements in the North and was determined to carry them through with or without water. Months later, the Government Agent (GA), Anuradhapura, told a low level briefing (Daily News 24 Jul.2013) that the construction of the Malwathu Reservoir by the Irrigation and Water Resources Management Ministry was to begin with plans for a settlement of 2100 ha just below the reservoir around Manik Farm (water requirement 63 mcm). The GA gave the estimated cost of the construction as Rs. 7.5 billion for the 285 mcm reservoir as against the Rs.28 billion contract to the Chinese for the 169 mcm Yan Oya reservoir. Evidently even China did not want to fund the Malwathu reservoir – one that appears to involve building the reservoir first and looking for the water later.[7]  

Aruvi-Malwathu River (known by its Tamil name downstream) feeds several medium-sized tanks.[8] We will use the information in the 1995 paper of Sakthivadivel et al[9], which relies on the measurements taken at the only river gauge at Kappachchi, just below the dam site for System I.[10]   

The Aruvi’s annual river flow is 713 mcm[11] of which 564 mcm or 79 percent of the total is used for irrigation. “Almost all the surface water potential in the four basins [of the NCP] (except Yan Oya) is [fully] utilized” (Sakthivadivel et al, ibid p.31). The 235 mcm mean annual flow at Kappachchi, becomes in two out of four years less than 159 mcm (the 50 percent dependable flow) and in one out of four, less than 84 mcm (the 75 percent dependable flow). The nature of the terrain is such that a marginal drop in rainfall leads to a sharp drop in river flow; the proportion of the reduction in river flow to reduction in rainfall, is far more drastic in the Malwathu-Aruvi Basin than for the Mahaveli Basin.[12] Owing to the heavy fluctuations, the 50 percent dependable flow, rather than the mean flow, is the basis for planning (Table 2.8 on Surface Water Availability in FN.9). [13]

Out of the flow at Kappachchi, 84 mcm is diverted downstream at Madhu Road to Giant’s Tank and Akattimurippu Kulam (Table 2.9 of FN.9). This is accomplished by the device of a tekkam, a barrage 12 feet high, across the flow of the river, which raises its level and permits lateral flow to the tanks along the channels ( designed by Henry Parker in 1881, S. Arumugam, Water Resources of Ceylon, p.331). The nature of the device ensures that irrespective of the river flow, a relatively constant quantity of water is sent to the two tanks. Given that more than 12,460 ha is cultivated under Giant’s tank, assuming the water duty for winter is 0.82 m as in Huruluwewa, the tank needs about 125 mcm for one season’s (winter’s) cultivation (it in fact receives 84 mcm p.a. from the Tekkam augmented by about 13 mcm of local flows[14]). We ignore the 16.6 mcm from 900 mm p.a. of precipitation on the surface of 4550 acres that is less than the average loss of about 1436 mm p.a. from evaporation.[15] The low water duty is suggested by the soils being mainly grumusols.[16]

Thus in a year of 50% dependable flow in Aruvi River (159 mcm), after the diversion to Giant’s tank, 75 mcm flows to the sea (total flow to the sea augmented by contributions downstream = 150 mcm, Tables 2.8 & 2.9, FN.9). Once in four years when the river flow is less than the 75% dependable flow of 84 mcm, there will almost be no water left after diversion to Giant’s Tank.

Consequences of Malwathu Reservoir for farmers under Giant’s Tank: What the foregoing tells us is that if the flow to Giant’s and Akaththimurippu Tanks is not meddled with, only a 75 mcm is available in a year of 50% dependable flow and none whatsoever in a year of 75% dependable flow.

The World Bank Report ‘Major Irrigation Rehabilitation Project’ of 6th November 1984 (No. 5231-CE) was the last major study involving the North before 25 years of war enveloped the region (hereafter referred to as WB 84). The irrigation systems dealt with are Kantalai (then 25 percent Muslim, 25 Tamil and 50 Sinhalese), Morawewa (then 40% Tamil and 25% Muslim), Iranamadu, Giant’s Tank (35 percent Muslim, 65 percent Tamil), Rajangana, Nachchaduwa (10 percent Muslim, 90 Sinhalese) and Huruluwewa.


WB 84 gave the cultivation intensity under Giant’s Tank as 88% (0.88) and placed 40 percent of the beneficiary population living below poverty level. Others in the low range of cultivation intensity were Morawewa 90% and Huruluwewa 100%. The rest were 120% and above. The greater contrast was in the per capita (annual) income per family member, which was Rs.400 p.a. for Giant’s Tank as against Rs.1830 in Iranamadu and Rs. 2060 for Rajangana, although the average land holdings were respectively 3.2 ha, 2.0 and 0.9. The last, Rajangana, had a cropping intensity of 1.63. All had average family sizes of 5.5, then compatible with Maritimepattu in Mullaitivu. The project sought to improve incomes through improving water supply and cropping intensity through the introduction of soya for alternative cropping during summer. The project was to last six years and owing to the constraint on water, envisaged the improvement in cropping intensity for Giant’s Tank only up to 95%, with 142.5% for Iranamadu (from 125%) and 150% and above for the rest.


For 25 years since that time, the people under Giant’s Tank suffered under both the Army and the LTTE, and particularly during the last phase of the war. The Muslims had been driven out by the LTTE in 1990. The consequences of the Malwathu dam would threaten the people’s tenuous existence. Notwithstanding promises of plenty of water and prosperity by the government, the people under Giant’s Tank, require an altogether new scheme as the principle of the present tekkam itself limits the flow p.a. to around 84 mcm.


WB 84 sought to improve the performance at Giant’s Tank System by: raising the full supply level of tank by one foot and re-modelling the tank feeder for 28.3 cubic metres/ sec (1,000 cubic feet/s) to divert to the tank part of the spill at Tekkam anicut (then about 40% of inflow). The envisaged returns for the whole project were:


Based on the hydrological studies, the assured cropping intensities with the project have been taken as: Kantalai, 150%; Huruluwewa, 150%; Nachchaduwa, 150%; Rajangana, 188%; Iranamadu, 143%; Giant’s, 95%; and Morawewa, 150%. 


These were modest improvements possible within the existing framework. Alternative cropping with Soya during summer (yala), was not recommended for the Giant’s Tank System, owing to the low availability of water in summer. Postwar, government ministers and irrigation officials have promised the Giant’s Tank farmers round the year cultivation, while in reality the outcome would be to take away even the little they have.


Besides, similar promises were made to hard pressed Sinhalese farmers in Padaviya with cropping intensities well below 1.0. The source of water has been identified – namely Moragahakande – however it turns out that these farmers would only get water to top up their cropping intensities to 1.0, because the bulk of the water has been reserved for the ideological settlement of Weli Oya. What chance do forgotten Tamil farmers under Giant’s Tank have of any good coming from the Government’s promises?


Given the nature of politics of this country, once Malwathu Reservoir is built there would be pressure to maximise the impounding of water with or without an alternative source, and maximise Sinhalese settlement. As we pointed out earlier, diverting more Mahaveli water would mean a phenomenal rise in the cost of electricity and it is for this reason that even Sinhalese farmers in the NCP have been denied additional water for nearly 30 years. 


The only justification one could find for the Malwathu Reservoir is the estimated figure of Aruvi River’s discharge to the sea of 568 mcm p.a. (Survey Department’s Sri Lanka Atlas 1988). This is not supported by the 159 mcm 50% dependable flow at Kappachchi (minus the diversion) based on actual river gauge measurements. The wide divergence in estimates by experts is a warning on the dangers these projects pose to the most helpless sections. Looking through irrigation literature, one finds careless guess work being passed on as authoritative figures for areas that are peripheral to politics.  

EN 10.4: System K and the Fate of the Iranamadu Farmer

In the absence of the NCP Canal the plan as presented by Minister de Silva (Island 1. Oct.2012) is for the putative Malwathu reservoir to feed System K (Kokkavil, Murikandi). In the 1969 Master Plan (see IAR), System K proposed to cultivate 8100 ha upstream of Iranamadu Tank below a dam to be built on Kanagarayan River, which also feeds Iranamadu Tank downstream to its north. According to IAR (op. cit.), of the annual 231 mcm of water the settlement requires, 166 mcm was to come from NCP Canal (which is no longer available) and the balance 65 mcm from local flow in Kanagarayan River. Even the 21,000 acres (8518 ha) of paddy land under Iranamadu requires annually 260 mcm; a minimum of 104 mcm just for the winter crop. The Iranamadu soils being mainly alluvial, we shall use Arumugam’s 4 ft. height of water for winter cultivation and 6 ft. for summer, in our estimates.[17] The current project being funded by the ADB envisages an annual 10 mcm of water to be sent from Iranamadu to Jaffna (IFAD).[18]

Kanagarayan River basin has an average annual runoff of 242 mcm[19] as estimated by P. Manchanayake and C.M. Madduma Bandara[20], and 220 mcm as given by U.A. Amarasinghe, L. Mutuwatta and R. Sakthivadivel.[21] The latter further tells us that the 75% dependable river flow is 120 mcm, while the 50% dependable flow, 180 mcm.[22]  There is a catch in this. The river basin map for Kanagarayan River is narrow in the south and broadens towards the sea. The river basin of 896 sq. km (ibid) can be divided into three portions as could be seen from p.92 of WB 84 (op. cit.): The first from the southern tip of the basin to the location of Kanagarayan Tank that was part of the NCP Canal Project covers 95 sq. km, the second from Kanagarayan Tank to Iranamadu Tank covers 506 sq. km. The flow from the balance 295 sq. km simply goes to the sea.

The foregoing tells us that the average local flow into the intended Kanagarayan Tank is roughly is 25 mcm (as distinct from the 65 mcm envisaged in IAR, op. cit.). The average flow into Iranamadu Tank obtained by reducing the total runoff in proportion to the catchment areas concerned, using the river flows from Amerasinghe et. al., is 147 mcm without Kanagarayan Tank and 123 mcm with Kanagarayan Tank; the corresponding 50% dependable flows are 121 mcm and 102 mcm and the 75% dependable flows 80 mcm and 68 mcm. We can check that the average of 147 mcm corresponds closely with the cropping intensity of 95% for winter and 30% for summer given by WB 84 (total 125%). In this respect IFAD’s cropping intensity of 150% for 2011 is not representative. We will look at the two sets of recommendations:

WB 84 (November 1984): raising the full supply level by one foot to utilize part of the spill (about 30% of inflow), repairs to spillway damage (1984 floods), and providing inverted filter at dam toe in areas showing seepage;


IFAD (2010): Under the ADB, AFD and Government financed Jaffna and Kilinochchi Water Supply and Sanitation Project of USD 134 million, about USD 10.6 million will be used to increase the capacity of the Iranamadu tank by 16.3 mcm to 148.1 mcm by raising the bund to 31.40m msl (103 feet). This will allow an extraction of water for Jaffna of 9.85 mcm per year.

Raising the bund by 1 foot (30 ft of water to 31 ft., water spread = 5750 acres – S. Arumugam) makes room for an additional 7.1 mcm. But the second plan envisages an additional 16.3 mcm of water out of which 9.85 mcm is sent to Jaffna. From the data above, even without Kanagarayan Tank, this would mean sending 9.85 mcm to Jaffna out of a 50% dependable flow of 121 mcm or in the one in four bad years, 9.85 mcm out of 68 mcm. In neither case would the Iranamadu farmer obtain the additional 6.45 mcm promised for local use as even the average annual flow without Kanagarayan Tank is just about the enlarged storage capacity of the tank and half the time the flow is much less. In other words, the tank will only exceptionally fill up. The 58 mcm of water left in a bad year after supplying Jaffna is just about enough for half the winter crop. We must remember that WB 84 judged the water situation in Iranamadu as ‘relatively short’ and the improvements suggested were modest and practical. In seeking to improve cropping intensity from 1.25 to 1.425, 0.025 was to be attained by improving rice cultivation in winter and 0.15 in summer by introducing soya cultivation. Kanagarayan Tank is clearly not viable without an external source of water, and that source cannot be the Malwathu dam, whose viability is in grave doubt as explained.

We seem to have modern planners who do not look at past studies, fail to consult local expertise, and move ahead on their own fantasies. Way back in 1971, the equivalent of Engineer in Society was introduced as a subject in the University of Ceylon to stress the importance of engineers being socially aware and responsible. The students at the time prided themselves that engineers as a profession in this country were head and shoulders above corruption and observed high ethical strandards. We now see the consequences of engineers becoming mixed up in politics and pelf.


The foregoing suggests that advancing Sinhalisation in the name of rehabilitating the war-affected, risks creating conditions of famine during periods of prolonged low rainfall. We need to keep in mind that small perturbations of conditions in the dry zone lead to drastic changes in the environment. A safety factor appropriate to the dry zone has been totally disregarded in pressing ahead with settlements. An observed trend in the last several decades (not necessarily long term) is declining average rainfall. Deforestation and other activities in the watershed, such as construction and intensive cultivation, degrade the water in rivers and interfere with flows. 



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[1]Initial Assessment Report – Updated Mahaweli Water Resources Development Plan, SMEC International Pty Ltd. in association with DHI Water and Environment (Denmark), Ocyana Consultants, Sri Lanka and Project Management Associates, Sri Lanka, Oct.2010

[2] The following from IAR gives the land area identified for cultivation in hectares (ha) and the amount of water each system was to receive from the NCP Canal to supplement local water availability in mega cubic metres (mcm – 1 mcm = 810.7 acre feet) and the additional reservoir capacity needed: I – 914 mcm, 52 900 ha, two reservoirs 294 mcm; J – 377 mcm, 22 8000 ha, two reservoirs 504 mcm; K – 166 mcm, 8100 ha, one reservoir 124 mcm; L – 985 mcm, 39 000 ha, two reservoirs 291 mcm; M – 106 mcm, 11 300 ha, one reservoir 235 mcm.

[3] UTHR Report No.11: “From that time Tamils became subject to small scale attacks by air force men and Sinhalese hooligans. The largest number of killings of Tamils took place along the Anuradhapura Road and the matter was raised in Parliament. This was the first instance in the island of the armed forces being stationed permanently in the middle of an agricultural scheme. The proportion of Tamils kept falling.”

[4] According to the report, apart from Tamil families (some of whom had fled to India) wanting their lands returned, notable applications were to regularise 200 acres the Sri Lankan Army had been using as a farming school, 40 acres for the archaeology department, and land to set up an army training camp. 

[5] Amaithipuram (7 mi north of Old Murikandi in the Thunukkai DS Division): 200 acres for the Commando Regiment. Kottaikattiyakulam (8 mi West of Old Murikandi): 150 acres on demand. Thenniankulam (7 mi NNW of Thunukkai): 46 acres for the armed services. Old Murikandy: 80 acres for the armed services. Therankandal (3 mi NNE of Thunukkai): 250 acres for the 53rd Division and 50 acres for the armed services. Alankulam (1 ½ mi NNE of Thunukkai): 112 acres on demand 



[6] Irrigation Secretary Ivan de Silva, quoted in Daily News 29 May 2012

[7] In 1961 the Soviet (now Russian) consultants Technopromexports prepared a project for Malwathu Reservoir with storage capacity 347 mcm (Arumugam), but other details such as sources of water are not easily accessible. Under the NCP Canal Project in the 1969 Master Plan there were to be two reservoirs Malwathu Reservoir with 275 mcm and Kapirigama upstream, near the Canal discharge, with 91 mcm.

[8]Among these tanks are Nachchaduwa, Mahakandarawa, Nuwarawewa, Iratperiyakulam, Pavatkulam, Akattimurippukulam, and finally Giant’s Tank, 32,000 ac. ft. or 40 mcm). According to IAR about 360 mcm is already used to irrigate 12,270 ha under medium-sized tanks and 8,830 ha under small tanks.

[9] R. Sakthivadivel, C.R. Panabokke, C.M. Wijeratna, Nihal Fernando, K. Jinapala, R.B. Bandula Sirimal; Pre-Project Technical Assistance Study for Proposed Area Development Project of North Central Province, Prepared for RH&H Consultant/ ADB, 1995

[10] The river basin area for Malwathu-Aruvi River is 1,210 sq. miles (3134 sq. km); the net catchment area has been estimated at 691 sq. mi (1790 sq. km) by Sakthi. 

[11] 101.6 mcm, from the Polgolla Diversion of 875 mcm, flows into Malwathu-Aruvi Subsystem (Table 2.5 & Plate 4 of Sakthivadivel et al, F.N.8). This water is used to support cultivation under Nachchaduwa, Nuwara Wewa and Tissa Wewa Tanks coming under System H, but has not added to cultivation in the Lower Basin. The area cultivated under IH remains at the pre-Mahaveli 4510 ha.

[12] Considering the mean, 50% and 75% dependable rainfall variations in Anuradhapura and Vavuniya from Table 2.3 of FN.8 with the mean, 50% and 75% dependable river flow in Aruvi River from Table 2.2 ibid; we see that a reduction of rainfall by 3.6 percent from the mean causes a reduction in river flow by about 32 percent from the mean. A reduction of rainfall by 19 percent from the mean results in a reduction of river flow by about 64 percent from the mean. From Table 2.2 of IAR, a reduction of 10% in rainfall in the Mahaveli basin caused a reduction of about 20% in river flow.

[13]“The strategy for water resources development should be to maximise productivity per unit of water in the Malwathu-Aruvi basin and to maximize productivity per unit of land in the Polonnaruwa District” – FN.8.

[14] 13.3 mcm, local flow from the 38 sq. mi. of catchment area (Arumugam) assuming 15% runoff compatible with Table 2.2 of Manchanayake and Bandara (op. cit.).

[15] Water Statistics Handbook, Irrigation Department, Colombo, 1988

[16] Grumusols (clay loan to clay) are characterized by low permeability and high available water and are very suitable for rice cultivation but need puddling for land preparation (WB 84 op. cit.).

[17] Alluvial soils (sandy clay loam to sandy clays) have higher infiltration rates and less available water. However, these soils are also being used entirely for paddy cultivation. Iranamadu soils are alluvial (deep sandy, shallow to moderately deep sandy) and clayey. The alluvial soils occur at higher levels. These permit tillage under dry conditions, can be maintained under saturated conditions because of clays below, and are therefore used extensively for rice in Maha. The clayey soils occur in valleys. (WB 84)

[18] The International Fund for Agricultural Development, Iranamadu Irrigation Development Project, October 2011: 

[19] The average rainfall (1265 mm), river ruoff (19.1%) and catchment area (907 sq. km.) for Kanagarayan Basin, given by Manchanayake and Madduma Bandara, yields a river runoff volume of 219 mcm.

[20]  Water Resources of Sri Lanka, National Science Foundation, 1999

[21] Water Scarcity Variations within a Country: A Case Study of Sri Lanka, IWMI, 1999

[22] We ignore the 25.6 mcm the 5750 acres of the tank spread receives from an average rainfall of 43.3 in p.a. since this is less than the average evaporation of 56.5 in

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